Bakery bag and method and apparatus for making the same

ABSTRACT

A new and improved bag is provided comprising a sheet of flexible, foldable material, wherein the sheet is coated on one side with metal to define a treated side and an un-treated side; wherein the sheet is folded along a fold line such that (i) the treated side faces outwards, and (ii) transversely opposite side edges are defined; wherein a gusset is provided by in-folding the fold line into the bag, thus defining gusseted bottom edges; wherein transversely opposite end portions of the gusseted bottom edges are angled edges that angle towards the fold line at a predetermined angle and end at the side edges; wherein the sheet is bonded together at adjacent side edges; and wherein the sheet is bonded together at adjacent angled edges that have un-treated sides facing each other. Also provided is a method and apparatus for manufacturing the bag.

This invention relates to flexible and foldable bags and more particularly, to bags designed to hold food products such as bread. This invention also relates to methods of manufacturing such bags and apparatuses to implement the methods.

BACKGROUND OF THE INVENTION

It is known to construct a plastic bag by folding a continuous sheet of a flexible material, such as thermoplastic, over on itself, then making an in-fold at the folded edge, to form a gusset, and then simultaneously cutting and heat sealing the folded sheet along spaced apart transverse lines that are perpendicular to the fold. Each individual bag formed in this manner has an “W” shaped cross section at the gusset. This type of bag is commonly referred to as a “bread bag” and is often used for packaging loaves of bread. The bread loaf is inserted into the bag through an open end that is opposite the gusset. The open end is then tied shut in an appropriate manner to often present what is called the “pony-tail” end of the bag.

When filled with goods, such as a loaf of bread, bags constructed in this manner have, where the each side sealed edge meets the bottom, a triangular shaped pocket folded into the bag. When the bag is not carefully packaged, the triangular shaped pocket may not fold perfectly inside and thus cause the bottom of the bag to deform or wrinkle. This is a particular problem as bread is often stocked on shelves with the bottom facing the consumer and the bottom contains the product identifying information and the supplier's trade-marks and logos. Product information and logos are often printed directly on the bag or affixed using a label. Furthermore, this pocket also makes printing material that wraps around the bottom to the sides of the bag difficult. Generally, the pocket does not provide for a very clean look particularly when viewed from the bottom or from the side as the bag is usually transparent or translucent. Furthermore, since traditional bread bags are often transparent, light incident on the food product can decrease the visual quality of the food.

There is therefore a need for improved flexible bags which solves the above problems and can be efficiently manufactured.

SUMMARY OF THE INVENTION

The present invention provides an improved flexible bag that has a clean square bottom and can be efficiently manufactured. The improved bag is particularly suited for containing food stuffs.

According to one broad aspect of the present invention, a bag is provided that has improved presentation and ability to keep food fresh comprising a sheet of flexible, foldable material,

-   -   (a) wherein the sheet is coated on one side with metal to define         a treated side and an un-treated side;     -   (b) wherein the sheet is folded along a fold line such that (i)         the treated side faces outwards, and (ii) transversely opposite         side edges are defined which are substantially perpendicular to         the fold line;     -   (c) wherein a gusset is provided centered along the fold line,         such that the fold line is in-folded into the bag, thus defining         gusseted bottom edges;     -   (d) wherein transversely opposite end portions of the gusseted         bottom edges are angled edges that angle towards the fold line         at a predetermined angle and end at the side edges;     -   (e) wherein the sheet is bonded together at adjacent side edges;         and     -   (f) wherein the sheet is bonded together at adjacent angled         edges that have un-treated sides facing each other.

According to another aspect of the invention, a method is provided for manufacturing the bag. The method comprises the following steps:

-   -   (a) coating one side of the sheet with metal defining a treated         side and an un-treated side;     -   (b) folding the sheet along a fold line such that the treated         side faces outwards;     -   (c) creating a gusset centered along the fold line by in-folding         at the fold line, thus defining gusseted bottom edges and a         gusset depth in a direction substantially perpendicular to the         fold line;     -   (d) making “V” shaped cuts through the gusset, at predetermined         intervals in a direction parallel to the fold line, such that         the corner of the “V” shape is positioned at a pre-determined         length from the gusseted bottom edge and the sides of the “V”         shape extends towards and end at the gusseted bottom edges;     -   (e) bonding the sheet together at adjacent edges cut in step (d)         that have un-treated sides facing each other;     -   (f) cutting along a line starting at said corner of each “V”         shaped cut and extending in a direction substantially         perpendicular to the fold line and ending at a top edge of the         bag; and     -   (g) bonding the sheet together at adjacent edges cut in step         (f).

According to another aspect of the invention, an apparatus is provided to simultaneously make an “V” or “Y” shaped cut and bond resultant edges using heat, comprising:

-   -   (a) a heated block;     -   (b) a blade, disposed to produce “V” shaped cuts, coupled to and         extending outwards from a top surface of the heated block;     -   (c) a lower plate (i) disposed over the heated block, (ii)         provided with a hole the shape of and slightly larger than the         blade and disposed to receive the blade, and (iii) spring loaded         for motion in a direction perpendicular to the top surface of         the heated block;     -   (d) an upper plate (i) disposed over the lower plate, (ii)         capable of motion in a direction perpendicular to the top         surface of the heated block, to press on the lower plate such         that the blade passes through the hole and contacts the upper         plate.

One advantage of present invention is that a bag with a square and flush bottom provides improved presentation. A square and flush bottom presents an improved surface for affixing labels or printing product information and logos. Furthermore, the bag increases the ease with which one can affix labels or print product information on the bag that wraps around the bottom to the sides. Generally, the bag gives an overall cleaner look.

Another advantage of the present invention is that it alleviates the problem of wrinkling and deforming that occurs when bags of the prior art are not carefully filled since the present invention does not have triangular shaped pockets on the bottom face.

Another advantage of the present invention is that by treating one side of the bag with a metal, such as aluminum, food products packages in the bag will stay fresh longer. Treating one side of the bag with metal also reduces the amount of light incident on the food product thereby maintaining the visual quality of the food.

Another advantage of the present invention is that it can be manufactured easily since the cutting and sealing can be performed in single step. This is due, in part, to the treating of one side of the bag with a metal.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of the preferred embodiments of the invention will become more apparent in the following detailed description in which reference is made to the appended drawings wherein:

FIG. 1 is a front elevation view of a flattened bag of the prior art.

FIG. 2 is a perspective view of a filled bag of the prior art.

FIG. 3 is a perspective view of a flattened bag according to the present invention.

FIG. 4 is a perspective view of a filled bag according to the present invention.

FIG. 5 is a front elevation view of a flattened bag without a lip according to the present invention.

FIG. 6 is a front elevation view of a flattened bag according to the present invention.

FIG. 7 is a cross section at line II-II of the bag of FIG. 6.

FIG. 8 is a side elevation view of a filled bag according to the present invention.

FIG. 9 is a front elevation view of a sheet of material showing the prospective cut and seal lines according to the present invention.

FIG. 10 is a front elevation view of a sheet of material with a triangular shape cut out at the gusset.

FIG. 11 is a side elevation view of an apparatus, for making the cuts and seals of the present invention, with an upper plate, heating block, blade and lower plate.

FIG. 12 is a front elevation view of the apparatus of FIG. 15.

FIG. 13 is a side elevation view of a partial apparatus, for making the cuts and seals of the present invention, with an upper plate, heating block and blade.

FIG. 14 is a front elevation view of the apparatus of FIG. 11.

FIG. 15 is a side elevation view of a partial apparatus, for making the cuts and seals of the present invention, with an upper plate and lower plate.

FIG. 16 is a front elevation view of the apparatus of FIG. 13.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following description, numerous specific details are set forth to provide a thorough understanding of the invention. However, it is understood that the invention may be practiced without these specific details. In other instances, well-known structures and/or processes have not been described or shown in detail in order not to obscure the invention. In the description and drawings, like numerals refer to like structures or and/or processes.

The methods of the present invention are claimed and described herein as a series of steps. It should be understood that these methods and associated steps may be performed in any logical order. Moreover, the methods may be performed alone, or in conjunction with other procedures and methods before, during or after such methods and steps set forth herein without departing from the scope and spirit of the invention.

FIGS. 1 and 2 generally show a bag of the prior art used to contain bread. Referring to FIG. 1, a flattened bag of the prior art is shown. The bag consists of a sheet of flexible material 110 comprising a top edge 105, bottom edge 106, side edges 103 and apertures 109 proximal to the top edge. The sheet 110 is folded along a fold line 107 substantially perpendicular to the side edges 103 to define (i) a front side 101 and a back side 102, (ii) an exposed portion 141 proximal to the top edge 105 such that the apertures 109 on the back side 102 are not covered, and (iii) an area of overlap 140 between the front side 101 and the back side 102. The fold line 107 is then tucked into the interior of the bag 200 (thus shown as a stippled line) to form a gusset 120 with a gusset height 130 and thus defining new gusseted bottom edges 108. The gusset 120 therefore has a cross-section at line I-I with an “W” shape. Significantly, bags of the prior art are manufactured by cutting and sealing along peripheral edges 103. This results in the peripheral edges 103 at the gusset 120 being bonded together. In other words, all four sheet portions forming the “W” shape of the gusset are bonded together at the edges.

Referring to FIG. 2, the bag of FIG. 1 is shown when expanded and filled with food product such as a loaf of bread. The sealing of the entire “W” shape at the gusset results in a triangular shaped pocket 150 at the peripheral edges of the bottom surface 116 when expanded. The pocket 150 is defined by folded edges 151, 152, 153 and 154. Folded edges 153 and 154 extend towards the interior of the bag 10. As discussed above, this triangular pocket has numerous disadvantages.

Referring generally to FIGS. 3, 5, 6 and 7, a bag 200 according to the present invention, shown lying flat, is provided. The bag of the invention comprises a sheet of flexible material which has been coated on one side with metal 210 to define a metal treated side 229 and an untreated side 230. The starting material for the sheet can be any suitable flexible material, preferably, a thermoplastic material. The flexible sheet can be coated with any suitable metal, although aluminum is preferred.

The sheet 210 similarly comprises the top edge 105, bottom edge 106, side edges 103 and the apertures 109 proximal to the top edge. The sheet 210 is folded along the fold line 107 substantially perpendicular to the side edges 103 to define (i) a front side 101 and a back side 102, (ii) an exposed portion 141 proximal to the top edge 105 such that the apertures 109 on the back side 102 are not covered, and (iii) an area of overlap 140 between the front side 101 and the back side 102. Importantly, as shown in FIG. 7, the sheet 210 is folded such that the metal treated side 229 forms the outside of the bag 200 and the untreated side 230 forms the inside of the bag 200. The fold line 107 is then tucked into the interior of the bag 200 (thus shown as a stippled line) to form the gusset 120 with gusset height 130 and thus defining new gusseted bottom edges 108. Referring specifically to FIGS. 6 and 7, the gusset 120 again has a cross-section at line III-III with an “W” shape.

Transversely opposite ends portions of the gusseted bottom edges 108 are angled edges 220 that angle upwards at a predetermined angle 225 and end at side edges 103. The angle 225 can be from 30-60 degrees but is preferably about forty-five degrees. Also, the angled edges 220 preferably end at the side edges 103 at about a gusset height's length from the gusseted bottom edges 108, thus ending about where the fold line 107 meets the side edges 103. The side edges 103 are bonded to each other. The angled edges 220, only of adjacent sheets that have un-treated sides 230 facing each other, are bonded to each other. Therefore, since the angled edges 220 are in the gusset 120 portion of the bag, only those portions of the sheet representing a peak on the “W” shape of the gusset 120 are bonded together.

Referring to FIG. 5, in one embodiment of the invention, the bag has no exposed portion 141 and no apertures 109 proximal to the top edge 105.

Referring to FIGS. 4 and 8, the bag 200 is shown when filled with food product such as a loaf of bread. When the bag 200 is expanded, the bag 200 presents a square and flush bottom and side without any folds or pockets. As discussed earlier, this absence of fold or pockets, along with the metal coating, results in a variety of advantages regarding presentation and freshness.

According to another aspect of the invention, a method is provided to manufacture a metal coated bag with a flush square bottom. The method comprises the following steps. Coating a flexible sheet with a suitable metal so that one side is treated and the other is un-treated. Folding the sheet along a fold line such that the treated side faces outwards. Creating a gusset of a pre-determined depth by in-folding at the fold line. Making an angular cut, in a “V” shape, on the sheet through the gusset such that the tip of the “V” is positioned at a pre-determined length from the gusseted bottom and the sides of the “V” extend towards and end at the gusseted edge. Bonding the sheet together at adjacent edges of the “V” shaped cut that have un-treated sides facing each other. Cutting along a line starting at the tip of each “V” shape and extending in a direction perpendicular to the fold line and ending at a top edge of the bag and then bonding the resulting edges together. This cutting and bonding is repeated along a length of the sheet, in a direction parallel to the fold line, to manufacture multiple bags.

The sheet can be of any flexible, foldable material, including but not limited to a thermoplastic material. Methods for producing a sheet of thermoplastic material are well known and typically consist of extruding a lay flat tube of thermoplastic material and edge slitting the lay flat tube on both sides to produce 2 layers of film.

Any suitable metal can be used to coat the sheet. Preferably, aluminum is used and methods to coat thermoplastic material using aluminum, such as for potato chip bags, are well known in the art and will not be described here. Coating thermoplastic materials can involve an intermediate treatment to enable the metal to adhere to the material.

Referring to FIG. 9, the “V” shaped cuts are shown as solid lines formed by line segments 901-900 and 900-902. In a preferred embodiment of the invention, the “V” shape has about a ninety degree angle. Referring to FIG. 10, a folded sheet is shown with multiple “V” shapes cut out along the length of the sheet. The bag is then bonded along the edges where the “V” shape cut has been made, but only where un-treated sides face each other. Thus, only the peaks of the “W” in the “W” shaped gusset, are bonded together and the valley in the middle of the “W” is not.

The cut extending from the corner of the “V” shape is shown as a solid line formed by line segment 900-903. The resultant edges are bonded together. This results in an overall cut in the shape of a “Y”. As generally illustrated by FIGS. 9 and 10, the manufacture of multiple bags is accomplished by repeating this “Y” shaped cut along the length of the sheet.

In a preferred embodiment of the invention, cutting and bonding are performed in a single step. This is possible since the sheet has been treated on one side with aluminum and this side is on the outside of the bag. When the edges are cut, bonding using heat is simultaneously performed. This advantageously only bonds the desired edges together. Cutting the “V” shape while heating the resultant edges will result only in the sheet portions forming the peaks of the “W” being bonded together because only the peaks have un-treated sides facing each other. In contrast, sheets portions forming the valley of the “W” shape will not be bonded together because the edges that face each other have been treated with a metal such as aluminum. With respect to the cut extending from the corner of the “V” shape, the resultant edges will have un-treated sides facing each other. Consequently, the edges will be bonded together as desired.

According to another aspect of the invention, an apparatus 500 is provided to simultaneously make the “V” or “Y” shaped cuts of the method described above. Referring to FIGS. 11 and 12, the apparatus 500 is comprised of a heated block 501, a “V” shaped blade 502, a lower plate 508 and an upper plate 505. Although a “V” shaped blade is preferable, it will be understood by those skilled in the art that blades of other shapes, such as a triangle, can create similar “V” shaped cuts. The blade 502 is attached to and extends outwards from a top surface of the heated block 501. Preferably, the heated block 501 is comprised of separable cast metal layers machined to hold a replaceable heating means.

The lower plate 508 is disposed over the heating block and comprises a metal stripper plate 510, an insulating plate 509 attached to a top surface of the stripper plate, and springs 503 that allow the lower plate 508 to move in a direction perpendicular to the top surface of the heated block 501. The springs 503 of the lower plate 508 are attached to a ground surface 520, preferably by shoulder bolts 504. The lower plate further comprises a hole the shape of and slightly larger than the blade 502 and disposed to receive the blade 502.

The upper plate 505 is disposed over the lower plate 508 and comprises a clamp plate 506 and a resilient surface 507 on an underside of the clamp plate 506. Furthermore, the upper plate 505 is capable of motion in a direction perpendicular to the top surface of the heated block 501. In some preferred embodiments of the invention, the upper plate is pneumatically driven.

In operation, the blade 502 is heated by the heater block 501. A sheet of material is placed in between the upper plate 505 and the lower plate 508. The upper plate 505 is driven downwards and presses on the lower plate 508. This causes the lower plate 508 to move down and the blade 502 to move through and exit the topside of the hole on the lower plate 508. The exiting blade 502 thus presses against the upper plate 505. This action results in a “V” shaped cut in the material in between the upper plate 505 and the lower plate 508 using the heated blade 502. Since the blade 502 is heated, suitable materials and surfaces will be bonded simultaneously with the cut. In another embodiment of the invention, a “Y” shaped blade is used to produce “Y” shaped cuts. FIGS. 13-16 illustrate a partial apparatus with different components showing in order to more clearly illustrate individual components.

Although preferred embodiments of the invention have been described herein, it will be understood by those skilled in the art that variations may be made thereto without departing from the spirit of the invention or the scope of the appended claims. 

1. A bag comprising a sheet of flexible, foldable material, (a) wherein the sheet is coated with a metal to define a metal treated side and an un-treated side; (b) the sheet being folded along a longitudinal fold line with the treated side facing outwardly and the untreated side facing inwardly, and the fold line being in-folded into the bag, thus defining a gusset centered along the fold line with at least two gusseted bottom edges; (c) transversely opposite side edges wherein the sheet is bonded together extending substantially perpendicular to the fold line; and (d) end portions of the gusseted bottom edges comprising angled edges wherein the sheet is bonded together extending from each gusseted bottom edge to the side edges at a predetermined angle relative to the gusseted bottom edge.
 2. The bag according to claim 1, wherein the predetermined angle is between 30-60 degrees.
 3. The bag according to claim 2, wherein the predetermined angle is about 45 degrees.
 4. The bag according to claim 1, wherein the angled edges end where a side edge meets the fold line.
 5. The bag according to claim 1, wherein apertures are provided proximal to a top edge of the bag.
 6. The bag according to claim 1, wherein the sheet is folded to also define an exposed portion proximal to a top edge of the bag.
 7. The bag according to claim 1, wherein the flexible foldable material is a thermoplastic.
 8. The bag according to claim 1, wherein the sheet is coated with aluminum.
 9. A method for manufacturing a bag using a sheet of flexible, foldable material comprising the steps of: (a) coating one side of the sheet with metal defining a treated side and an un-treated side; (b) folding the sheet along a fold line such that the treated side faces outwards; (c) creating a gusset centered along the fold line by in-folding at the fold line, thus defining gusseted bottom edges and a gusset depth in a direction substantially perpendicular to the fold line; (d) making “V” shaped cuts through the gusset, at predetermined intervals in a direction parallel to the fold line, such that the corner of the “V” shape is positioned at a pre-determined length from the gusseted bottom edge and the sides of the “V” shape extends towards and end at the gusseted bottom edges; (e) bonding the sheet together at adjacent edges cut in step (d) that have un-treated sides facing each other; (f) cutting along a line starting at said corner of each “V” shaped cut and extending in a direction substantially perpendicular to the fold line and ending at a top edge of the bag; and (g) bonding the sheet together at adjacent edges cut in step (f).
 10. The method according to claim 9, wherein steps (d) and (e) are performed simultaneously.
 11. The method according to claim 9, wherein steps (f) and (g) are performed simultaneously.
 12. The method according to claim 9, wherein steps (d), (e), (f) and (g) are performed simultaneously.
 13. The method according to claim 9, wherein the “V” shape forms about a ninety degree angle.
 14. The method according to claim 9, wherein the tip of the “V” shape is positioned a gusset depth's length from the gusseted bottom edges.
 15. The method according to claim 9, wherein the flexible foldable material is a thermoplastic.
 16. The method according to claim 9, wherein the sheet is coated with aluminum.
 17. A bag of flexible, foldable material manufactured according to the method of claim
 9. 18. A machine for simultaneously making a cut and sealing resulting edges on a sheet of flexible material comprising: (a) a heated block; (b) a blade, disposed to produce “V” shaped cuts, coupled to and extending outwards from a top surface of the heated block; (c) a lower plate (i) disposed over the heated block, (ii) provided with a hole the shape of and slightly larger than the blade and disposed to receive the blade, and (iii) spring loaded for motion in a direction perpendicular to the top surface of the heated block; (d) an upper plate (i) disposed over the lower plate, (ii) capable of motion in a direction perpendicular to the top surface of the heated block, to press on the lower plate such that the blade passes through the hole and contacts the upper plate.
 19. The apparatus according to claim 18, wherein the heated block comprises separable cast metal layers machined to hold a replaceable heating means.
 20. The apparatus according to claim 18, wherein the lower plate comprises a metal stripper plate and an insulating plate attached to a top surface of the stripper plate.
 21. The apparatus according to claim 18, wherein the upper plate comprises a metal clamp plate and a resilient surface on an underside of the clamp plate.
 22. The apparatus according to claim 18, wherein the blade is disposed to produce “Y” shaped cuts.
 23. The apparatus according to claim 18, wherein the flexible material is a thermoplastic.
 24. The apparatus according to claim 18, wherein the upper plate is pneumatically driven in a direction perpendicular to the top surface of the heated block. 